Man's body found floating off SA jetty

A man's body has been found floating off a popular Adelaide beach.

The man, aged in his 40s, went for a swim off the Glenelg jetty about 7.50am (CDT) on Saturday.

Police say onlookers saw him go underwater, but he did not resurface.

Emergency services were alerted and half an hour later a member of the public on a paddle board found his body floating in the water.

Police and paramedics conducted CPR but they were unable to revive the man.

A report is being prepared for the coroner and police have urged anyone who saw the man before he swam off the jetty to call 1800 333 000.